Amylose in the reduction of pour point



United States Patent C) ice Filed July 8, 1965, Ser. No. 470,486 11Claims. (Cl. 20828) ABSTRACT OF THE DISCLOSURE Amylose is utilized toform a complex with normal parafiins in order to remove them fromvarious mixtures. In particular, amylose is used to form a complex withlong chain or waxy normal paraffins in order to remove them from ahydrocarbon fraction and thereby lower their pour point.

This invention pertains to an improved method for removing normalparafiins from hydrocarbon mixtures.

The normal parafiins may be of any length although they must be capableof forming an inclusion compound. Thus, this invention relates to theremoval of normal parafiins from naphthas, kerosene, gas oils andheavier hydrocarbon cuts. With more particularity, this inventionpertains to the lowering of the pour point of paraffinic lubes andspecialty oils by removing the long chain normal paralfins whichcontribute to the high pour point, To accomplish this purpose accord ngto this invention, starch amylose is contacted with the normal parafi'incontaining compound; this starch amylose forms a complex or inclusioncompound with the normal parafiins. After the inclusion compound isformed, it can readily be removed by filtration. The invention will bediscussed with respect to the dewaxing of paraflim'c lubes and specialtyoils but it will be readily apparent to one skilled in the art that thesame procedure is equally applicable to removing paraflins from otherhydrocarbon mixtures such as naphthas, kerosenes and gas oils.

In recent years the demand for low pour point lubricating oils hasbecome extremely high. This is due to a large extent to the greaterdemand for these oils in regions which experience acute winters. Suchregions include Northern United States, Canada, the Scandinaviancountries and Switzerland to name just a few. A great variety of lubesand specialty oils must fulfill this requirement of low pour point;typical of these materials are transformer and white oil base stocks aswell as motor oils.

This problem is not new although it has increased in the last few years.For decades now a variety of different methods have been used toaccomplish the production of a low pour point oil. However. all of themhave presented very serious drawbacks which have hindered their use.

Perhaps the two most well-known of these methods are methyl ethyl ketonedewaxing and propane dewaxing; certainly they are the most Widely useddewaxing processes which are capable of getting a pour point down to F.

These processes are successful to some degree however,

they are not capable of producing oils with below 0 F. pour points. MEKcan give low pour point oils but not economically; further, when usingMEK, troubles are encountered while running bright stocks. Propanedewaxing is definitely limited to 0 F. pour points because the loweratmospheric pressure needed for lower chiller temperatures are adistinct safety hazard with propane. This is because any leakage of airinto the system would form a combustible mixture with the propane.

As an alternative, the addition of urea to these waxy oils in order toform adducts between the urea and the Patented Nov. 28, 1967 normalparafiins has also been used to achieve very low pour point lubes. Thismethod, like the other known dewaxing methods, is also extremelyexpensive. In addition, those who have worked with this method haveencountered a substantial problem with corrosion and 0perability. Thenature of urea is such as to cause a good deal of difficulty since it isa highly corrosive material. Liquid urea systems, especially aqueoussystems, have exhibited difiiculties with emulsions and foams as well asa substantial filtration problem. Urea is also inelfective in producinglow pour bright stock.

According to this invention, these problems have now been solved. Thisinvention concerns the addition of starch amylose to a Waxy oil solutionwhereby the starch amylose forms an inclusion compound with the normalparaifins and thereby removes them from the Waxy oil solution. Theresulting oil has a considerably lower pour point since it is thesenormal parafiins that contribute to the raising of the pour point.

The starch amylose complex forms when the amylose helix selectivelycoils around the normal parafiin molecule. The resulting complex can befiltered out of solution and decomposed to regenerate the amylose. Afterthe complex is formed, it is washed for oil removal and then sent to acomplex splitter, Here the complex is decomposed into amylose and normalparafiins. Decomposition occurs when temperatures and concentrations arevaried so as to destroy the original equilibrium reaction or complexformation. This is done by contacting the complex With hot naphtha,alcohol, water, steam or other Wellknown complex splitting agents whichhave previously been heated to the appropriate temperature of 100 to 400F., preferably 200 to 300 F. The regenerated amylose is recycled whilethe wax may be sent directly to fuel or otherwise treated to recovercomplex splitting agents or to permit its use as a product.

In this manner, the great expense associated with the use of urea iseliminated since starch is a far less costly item and amylose mayreadily be obtained from starch. Furthermore, the diflicultiesassociated with corrosion caused by the urea are also eliminated.Amylose is one of the two major constituents of starch. The other majorconstituent being amylopectin; of the two major constituents amylopectinis present in a far greater amount. However, amylose may be readilyobtained from starch by complexing the amylose out of a dilute dispersedstarch solution with butanol. Commercially, there is a process thatconsists of preparing a molecular dispersion of starch and reacting itin concentrated salt solutions followed by fractionating the amylose andamylopectin at controlled temperatures. Amylose is water-soluble and isprimarily responsible for the blue color obtained by the addition ofiodine to starch. There is about 4 times as much amylopectin in starchas there is amylose; this will vary with the particular carbohydrates.Amylose is a linear polymer and consists of 200 to 1000 glucopyranoseunits joined to each other through aIA-gluosidic linkages. Amylose, whenstarch is dispersed in water, forms an insoluble complex with butylalcohol which may be sedimented by centrifugation. The exact amount ofamylose within a given starch will vary, starches from socalled waxygrains, as exemplified by waxy corn contains substantially no amylose;whereas starch from certain varieties of peas may contain as much as Thecommon industrial starches contain roughly 15 to 30% by weight ofamylose. There is also now being bred a hybrid corn which would containamylose, such a product would be especially attractive for the instantinvention. About 10 to 70% by weight of amylose is to be added to amineral oil which is to be dewaxed. Preferably about 10 to 50 wt.percent of amylose is added and most preferably 10 to 30 wt. percent ofamylose is introduced into the mineral oil. Among the oils to be treatedby this invention are lubricating oils which pour between 60 and 120 F.After treatment with amylose, the oils will pour between 50 and 10 F.Specialty oils, transformer oils and low viscosity blend stocks for 10Wand 10W-30 motor oils will have their pour points reduced about 95 to 50F. by the instant invention.

With respect to conditions, an inclusion compound between amylose andnormal paraflins may be formed at a temperature within the range of to300 F., preferably 70 to 100 F. and most preferably 50 to 80 F.Pressures for the formation of the inclusion compound of the instantinvention may vary between 0 and 200 p.s.i.g., prefer-ably 100 and 150p.s.i.g. An activator or mutual solvent as exemplified by methanol,propanol, isopropyl, alcohol, acetone, ketones and C to C aldehydes maybe used to speed up the complexing step. These activators may beutilized in trace amounts. However, these activators are not absolutelynecessary and the reaction will proceed for the most part satisfactorilywithout them.

Contacting times between the amylose and the waxy oil will vary frombetween 5 to 180 minutes, preferably 5 to 30 minutes and most preferably5 to minutes. For purposes of this invention a waxy oil may be definedas an oil which contains about 10 to 25 wt. percent of normal parafiinsbetween C and C The amylose may be added in the solid state or may be insolution. If added in solution, about 90 to 95% by weight of water isadded along with the amylose.

The resulting solid inclusion compound is separated from the oilsolution and is decomposed by heating it at a relatively hightemperature or other means such as reaction equilibrium shift viaconcentration efiect. The amylose-waxy complex is separated from thelube oil by simply gravity settling, conventional filtration,centrifugation or other equivalent techniques which are well-known inthe art. The complex which is in the form of a filter cake is washed foroil removal and then sent to a complex splitter, Within the splitter,the complex is decomposed into amylose and normal paraffins. Most of thenormal paraflins are in the range of C to C As mentioned previously,decomposition occurs when temperatures and concentrations are varied soas to destroy the original equilibrium reaction or complex formation.This may be done by contacting the complex with hot naphtha, alcohol,water, steam or other well-known complex splitting agents which Wereheated to the needed temperature for complex destruction thistemperature would be between 200 and 300 F. The regenerated amylose isthen recycled back to the reaction While the wax may be sent directly tofuel or otherwise treated to recover the complex splitting agent if onehas been added. The recovered wax may be also used as a product.

The attached figure is a schematic representation of the instantinvention.

A waxy oil is introduced through line 1 and passes into heat exchanger 2where it is raised to a temperature of 100 to 300 F. The waxy oil isremoved through line 3 and passes into contactor 4. This contactor issupplied with agitation means 5. Solid amylose is stored within amylosehopper 6, This amylose is easily obtained from commercial firms. Theamylose is removed from the bottom of hopper 6 through line 7 and passedinto contactor 4. Contactor 4 is maintained at a temperature of 100 to300 F. and a pressure of 100 to 200 p.s.i.g. This temperature andpressure is mainta'med in the initial contacting stage, after which thereacting mixture is cooled in the contactor to ambient temperature so asto facilitate crysallizaion of the complex. As an alternate feature, amutual solvent such as a lower alcohol, ketone such as acetone or C to Caldehyde may be introduced as a promoter. This mutual solvent is storedin storage tank 8 and removed through line 9 from which it is passedinto contactor 4. Amylose, waxy oil (which contains about 10 to 25% of Cor higher normal parafiins) and a mutual solvent activator are contactedwith agitation from agitators for a period of about 5 to 60 minutes. Atthe end of this time, the inclusion compound or complex is formed. About10 to 50 wt. percent of amylose is added for every Weight of waxy oil,about 1 to 5 wt. percent of alcohol is also added per weight of waxyoil.

This treatment results in the removal of about 10 to 25% of the C plusnormal paraflins which are in the waxy oil. Dewaxed lube oil, unreactedstarch amylose and the amylose-wax complex pass through line 10 intofilter 11 Where the wax-amylose complex and unreacted starch is removedas filter cake. Filter 11 may be any conventional filters such as rotaryvacuum or pressure or plate and frame. Other means of separation such ascentrifugation or simple gravity settling are also possible. Additionalmutual solvent may be passed from storage tank 8 through line 12 toserve as a solvent wash during the filtration process. Spent wash isremoved through line 12 and if desired may be recycled back to line 9 tobe used as a promoter in complex formation. The complex is removed fromfilter 11 through line 13 and passed through complex splitter 15. Withincomplex splitter 15, the complex is destroyed by means of heat anddiluent which could be naphtha, alcohol, water, steam or some otherwel-known compex spitting agent. The temperature within complex splitter15 is between and 300 F. Hot alcohol is added to the splitter to helpefiect the separation. The normal paraffin wax is removed from complexsplitter 15 through line 16. Wet amylose is removed from the splitter 15through line 17 and recycled through line 17 back to line 7 whence itmay be used again within contactor 4. The Wax passes through heatexchangers 18 and 19 and finally into evaporator 20. Purified wax isthen removed from the bottom of evaporator 20 through line 21. These arenormal paraflins having a weight of C to C From the top of theevaporator 20, mutual solvent is removed through line 22 and passesthrough heat exchanger 19' wherein the mutual solvent is condensed. Fromheat exchanger 19 the mutual solvent is passed through line 23 and theninto line 24 Where it once again may be passed into splitter 15. Anyadditional make-up mutual solvent is introduced into line 24 throughline 25.

Dewaxed oil is removed through line 26, passed through heat exchanger 27where the dewaxed oil is approximately 300 F. The dewaxed oil afterpassing through heat exchanger 27 cont ues along line 26 from whence itis passed into a second heat exchanger 28' wherein the dewaxed oil isheat-exchanged with condensing mutual solvent. Following this thedewaxed oil is passed into line 29 where it is transported to evaporator30. Mutual solvent, which has served as a promotor, is removed overheadfrom evaporator 30 through line 31 and sent to condenser 28 where it iscondensed. After passing through condenser 28, the mutual solvent ispassed into line 32 where it may return to the mutual solvent storagetank 8 or be further passed through line 25 to be used in the complexsplitter. For purposes of this invention, the mutual solvent utilizedwas 2 propanol, however, other organic promoters may be utilized such asmethanol, propanol, C to C aldehydes and ketones. The dewaxed oil isremoved from the bottom of evaporator 30 through line 33 and passed intoheat exchanger 36. Finally, dewax'ed oil at a temperature of to F. isremoved from the heat exchanger 35. This dewaxed oil has a pour point of-10 to 20 F. which represents an improvementof 20 to 30 F. over the pourpoint the oil originally had prior to introduction into the system ofthe instant invention.

This refers to second stage dewaxing. It is anticipated that the samefinal pour point could be achieved with single stage amylose dewaxing.

assasi Example In an actual example of the instant invention, a waxy oilwhich was a Solvent-100 Neutral having a viscosity of 105 SSU at atemperature of 100 F. was contacted with solid starch amylose. About 100cc. of the waxy oil were contacted with 50 grams of solid starchamylose. The amylose was obtained from commercial sources. The oilcontained about 12 grams of wax. About 60 cc. of isopropyl alcohol and 1volume of heptane diluent per volume of oil were vigorously mixed in abeaker. The complex and unreacted amylose were separated from thediluted oil by filtration. Distillation of the filtrate gave asolvent-free oil for a pour point analysis. The dewaxed oil had a pourpoint of 65 to 75 F. This indicates a lowering of the pour point by 20to 30 F. In the beaker, the temperature was maintained at 70 to 140 F.for a period of 30 to 180 minutes, pressure during this time wasmaintained under ambient conditions.

Although this invention has been described with some degree ofparticularity, it is intended only to be limited by the attached claims.

What is claimed is:

1. An improved process for lowering the pour point of a waxy oilfraction, the said waxy oil fraction pouring at a temperature of 60 to120 F. and containing waxy long chain normal parafiins which comprisescontacting the said waxy oil fraction with l-70 wt. percent of amylosewhereby a complex forms between said amylose and said long chain normalparaflins, the said contacting taking place at a temperature of 0 to 300F. and a pressure of 0 to 200 p.s.i.g. for a period of 5 to 180 minutes,filtering the said waxy oil whereby the said complex is removed and adewaxed oil is obtained which pours at a temperature of --50 to F.

2. The process of claim 1 wherein said complex is passed to a complexsplitting zone whereby the complex is subjected to a temperature of 200to 300 F. and the said complex is broken whereby the amylose isrecovered.

3. The process of claim 1 wherein the said long chain normal parafiinshave a length of at least C 4. The process of claim 1 wherein a solventactivator is added during the said contacting step to facilitate theformation of the said complex.

5. The process of claim 1 wherein the said activator is selected fromthe group consisting of methanol, pro- 6 panel, isopropyl alcohol andmethyl ethyl ketone, acetone and C to C aldehydes.

6. An improved process for lowering the pour point of a waxy oilsolution, the said waxy oil solution containing waxy long chain normalparaflins which comprises contacting said waxy oil solution with 10 towt. percent of amylose and a solvent activator at a temperature of 0 to300 F., a pressure of 0 to 200 p.s.i.g. for a period of 5 to 180 minuteswhereby a complex is formed between the said amylose and the saidparafiins, filtering the said solution to remove the said complexwhereby a lower pouring dewaxed oil is obtained, passing said complex toa complex splitting zone, splitting said complex by subjecting it toelevated temperatures within the said splitting zone, removing aseparate amylose stream from said complex and a separate stream of longchain normal parafiins.

7. The process of claim 6 wherein the said separate amylose stream isrecycled and used in the said contacting step.

8. The process of claim 6 wherein said activator is selected from thegroup consisting of methanol, propanol, isopropyl alcohol, acetone,ketone and C to C aldehydes.

9. An improved process for lowering the pour point of a waxy oilsolution, the said waxy oil solution pouring at a relatively elevatedtemperature and containing C through C long chain normal paraflins whichcomprises contacting said solution with 10-70 wt. percent of amylosewhereby a complex forms between said amylose and said long chain normalparaflins, the said contacting taking place at a temperature of 0 to 300F. and a pressure of 0 to 200 p.s.i.g. for a period of 5 to 180 minutes,filtering said waxy oil whereby the said complex is removed andobtaining a dewaxed oil with a reduced pour point.

10. The process of claim 1 wherein said waxy oil solution is a lube oil.

11. The process of claim 1 wherein the complex is separated into amyloseand parafiin after being filtered by subjecting it to elevatedtemperatures.

References Cited Die Starke, pages 349-354 by French et al., Oct. 15,1963.

DANIEL E. WYMAN, Primary Examiner. P. KONOPKA, Assistant Examiner.

1. AN IMPROVED PROCESS FOR LOWERING THE POUR POINT OF A WAXY OILFRACTION, THE SAID WAXY OIL FRACTION POURING AT A TEMPERATURE OF 60 TO120*F. AND CONTAINING WAXY LONG CHAIN NORMAL PARAFFINS WHICH COMPRISESCONTACTING THE SAID WAXY OIL FRACTION WITH 10-70 WT. PERCENT OF AMYLOSEWHEREBY A COMPLEX FORMS BETWEEN SAID AMYLOSE AND SAID LONG CHAIN NORMALPARAFFINS, THE SAID CONTACTING TAKING PLACE AT A TEMPERATURE OF 0 TO300*F. AND A PRESSURE OF 0 TO 200 P.S.I.G. FOR A PERIOD OF 5 TO 180MINUTES, FILTERING THE SAID WAXY OIL WHEREBY THE SAID COMPLEX IS REMOVEDAND A DEWAXED OIL IS OBTAINED WHICH POURS AT A TEMPERATURE OF -50 TO10*F.